1) Field of the Invention
The invention herein relates to a fabrication method for a flange-type ball valve that consists of the forging the initial two blanks of the water inlet seat and the ball valve seat for a one-piece flange-type ball valve, based on the blueprints of conventional one-piece flange-type ball valves, with the water inlet seat having a left pipeline connection section already formed inside and the ball valve seat having a ball valve chamber, its contiguous water outlet port, and a right pipeline connection section already formed inside. To facilitate easier finishing, a shallower mating section is formed at the front end of the water inlet seat for contact with the ball valve chamber of the ball valve seat. A left water-tight gasket containment recess is then lathed in the mating section end surface of the water inlet seat and external threads are died along the outer sides of the mating section. Furthermore, internal threads are tapped in the connection hole at the front end of the ball valve chamber of the ball valve seat to enable the screw fastening of the external threads of the water inlet seat into the connection hole. A right water-tight gasket containment recess is formed at the adjoining end surfaces between the water outlet port and the ball valve chamber and then a handle mounting hole is drilled. After the left and the right water-tight gaskets are inserted into the left and the right water-tight gasket containment recesses, the ball valve is placed inside the ball valve chamber. Then, the external threads of the water inlet seat mating section are coated with a thread locking agent and screw fastened to the internal threads in the connection hole of the ball valve seat which causes the left and the right water-tight gaskets to rest against the two spherical surfaces of the ball valve. As such, the ball valves fabricated according to the method of invention herein retain forged material strength, while avoiding the occurrence of pitting, reducing defect rates, allowing easier finishing, lessening material wastage, lowering production costs and, furthermore, minimizing component fabrication and shortening the manufacturing time.
2) Description of the Prior Art
Conventional metal flange-type valves are generally all cast fabricated because a one-piece flange-type ball valve can be produced as a single structural entity and, furthermore, most of the interior and exterior features of the said initial blanks are already formed after being cast into shape and only require the finishing and drilling of various sections to complete the valve. However, cavitation readily occurs during the casting process and to lessen the fine surface pitting resulting from the said cavitation, the initial blanks are given additional thickness and then the actual thickness required is achieved by interior and exterior finishing. While this reduces fine pitting, the material removed constitutes an enormous waste and, furthermore, the complete elimination of the said pitting is not possible. As a result, defect rates tend to increase and defective products that are marketed may leak. Soldering or welding during maintenance could unavoidably result in explosions or fires, which are common disasters often observed.
Due to the said shortcomings of ball valves that are fabricated by casting, the industry expected to avoid pitting flaws by forging the valve blocks. Referring to FIG. 1, the initial blank A of a forged one-piece flange-type valve of typical manufacture achieved the objective of single-entity shaping while still utilizes horizontal forging technology, but because of the limitations on easily opening the dies after forming, a die removal angle had to be included inside the die which left the vertically oriented border of the die release angles A1 that facilitated the opening of the die and, furthermore, the water inlet port and the water outlet port A2 and A3 as well as the ball valve chamber A4 could not be formed at the same time the one-piece flange-type ball valve A was forged and the said one-piece flange-type ball valve A remained an initial blank of solid construction that still required the forming of the internal aspects of a ball valve such as the removal of the invisible line section A5; referring to FIG. 2, to enable the placement of the ball valve of the ball valve chamber A4, the plug C was additionally fabricated and, furthermore, external threads C1 had to be tapped on the outer section and the right water-tight gasket containment recess C2 had to be formed on the front end; a left water-tight gasket containment recess A41 had to be formed at the bottom end of the ball valve chamber A4 which required the machining of considerable depth in the bottom end, with the said depth involving a high degree of difficulty that was obviously not a simple finishing task; then, the external threads C1 of the plug C were coated with a thread locking agent a fastened to the internal threads A31 in the water outlet port A3 at the right side of the one-piece flange-type ball valve A, causing the water-tight gasket D of the plug C to rest against the spherical surface of the ball valve B; due to the conventional structure, the said plug C is indispensable to the one-piece flange-type ball valve, with the fabrication and machining of the said plug C increasing the both production cost and time; therefore, conventional one-piece flange-type ball valves, whether cast or forged, involves a very high material cost, finishing is inconvenient due the weight that must be conveyed and, furthermore, the finishing procedure is quite complex and results in a wasting of material; forging was assumed to be a solution for the shortcomings of cast fabrication, but since the material cost remained high, finishing required much time, and the price was expensive, the product did not impress users and could not be successfully promoted to consumers because further improvement was still necessary.
Therefore, in view of the said shortcomings, the inventor of the invention herein addressed the said drawbacks by conducting research based on many years of experience in the field of ball valve production, with efforts finally culminated in the research and development of the invention herein which is hereby submitted in application for the granting of the commensurate patent rights.